chive__date">';
                    $html .= sprintf(
                        // translators: %s is the campaign send date.
                        esc_html__('(%s)', 'mailchimp-for-wp'),
                        esc_html(date_i18n(get_option('date_format'), $timestamp))
                    );
                    $html .= '</span>';
                }
            }

            $html .= '</li>';
        }

        $html .= '</ul>';

        return $html;
    }

    /**
     * Fetch sent campaigns from the Mailchimp API, with transient caching.
     *
     * Results are cached for 1 hour per (count) combination to reduce API requests.
     *
     * @since 4.13.0
     * @param int $count Maximum number of campaigns to retrieve.
     * @return array|string
     */
    private function get_campaigns($count)
    {
        $transient_key = 'mc4wp_campaigns_v2_' . $count;
        $cached        = get_transient($transient_key);

        if (false !== $cached) {
            return $cached;
        }

        try {
            $api = mc4wp_get_api_v3();

            $result = $api->get_campaigns([
                'status'        => 'sent',
                'count'         => $count,
                'sort_field'    => 'send_time',
                'sort_dir'      => 'DESC',
                'fields'        => 'campaigns.id,campaigns.settings.title,campaigns.settings.subject_line,campaigns.send_time,campaigns.long_archive_url',
            ]);

            if (is_object($result) && isset($result->campaigns) && is_array($result->campaigns)) {
                $campaigns = $result->campaigns;
            } else {
                return current_user_can('manage_options') ? '<!-- MC4WP Campaign Archive: Invalid API response format -->' : '';
            }
        } catch (MC4WP_API_Exception $e) {
            // Log API errors gracefully, do not break the page.
            mc4wp('log')->error('Campaign Archive: ' . $e->getMessage());
            return current_user_can('manage_options') ? '<!-- MC4WP Campaign Archive Error: ' . esc_html($e->getMessage()) . ' -->' : '';
        }

        if (empty($campaigns)) {
            return current_user_can('manage_options') ? '<!-- MC4WP Campaign Archive: Zero campaigns returned from Mailchimp. -->' : '';
        }

        set_transient($transient_key, $campaigns, HOUR_IN_SECONDS);

        return $campaigns;
    }
}